Membrane type fluid pump

ABSTRACT

The diaphragm pump includes a housing having an opening defined at one end. A diaphragm is attached to the housing and extends over the opening. An inlet is defined in the housing for receiving a fluid and a driving element is attached to the housing and in driving engagement with the diaphragm to vibrate the diaphragm. An orifice is defined in the diaphragm to permit a discharge of the fluid therethrough when the diaphragm is in vibration. A spring is disposed within the housing for biasing a plunger towards the diaphragm so that the plunger sealingly engages the diaphragm.

TECHNICAL FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to membrane type fluid pumps where amembrane serves as a wall of a chamber and is made to oscillate by meansof electromagnetic and piezoelectric driving means. The membrane causesa fluid disposed inside the chamber and inside the membrane to flow outthrough one or more holes defined in the membrane.

The known constructions have the drawback of unavoidable leaking thattakes place when the driving means are shut off and fluid leaks throughthe opening or openings defined in the prior art constructions.

One object of the present invention is to provide a new type of membranepump that does not leak when the pump is not operating.

SUMMARY OF THE INVENTION

One preferred embodiment of the present invention is a membrane typefluid pump having a chamber defined therein that is in fluidcommunication with a fluid container. The fluid pump also has a drivingmember, a membrane that closes one open side of the chamber and at leastone hole defined in the membrane. The driving member has the ability tocause the membrane to oscillate or swing. One novel feature of thepresent invention is that a plunge like body is disposed within thechamber and biased by a spring. The body is displaceable relative to thechamber and the membrane and has an end surface that adheres to the sideof the membrane when the membrane is in a rest position. Morespecifically, the body adheres to the side of the membrane that facestowards the interior of the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of a preferred embodiment ofthe membrane type pump of the present invention.

FIG. 2 is a schematic cross sectional view showing a portion of thepresent invention in a smaller scale when the pump is in a closed restposition.

FIG. 3 is a schematic cross sectional view when the pump is in anoperational position.

FIG. 4 is a schematic cross sectional view when the pump is in anoperational position.

FIG. 5 is a side view of a portion of a second embodiment of the presentinvention.

FIG. 6 is a side view of a portion of a third embodiment of the presentinvention.

FIG. 7 is a side view of a portion of a fourth embodiment of the presentinvention.

DETAILED SPECIFICATION

With reference to FIG. 1, a casing or housing 1 is shown. The casing 1has a bottom 2 and an enclosing wall 3 that is attached to a peripheryof the bottom 2. A recessed bore 4 is defined by a cylindrical wallportion 5 and a bottom 6 at the center of the bottom 2. The wall 3 has afree edge defining a step-like recess 7 for receiving a diaphragm 8 anda preferably annular driving core operating member 9. The casing 1 alsoincludes a nipple 10 or the like for defining a fluid channel forcarrying fluid from a container or other fluid source.

Adjacent to a central portion of the diaphragm 8 is preferably one ormore perforations 11 defined.

A plunger 12 is inserted into the central cylindrical recess 4 insidethe casing 1. The plunger 12 may, for example, be a cylindrical bodyhaving an end surface 13 that is facing outwardly toward the diaphragm8. The plunger 12 may also have an inwardly facing end surface having acompression spring 14 disposed between the bottom 6 and the inwardlyfacing end surface.

FIGS. 1 and 2 illustrate the position of the diaphragm 8 and the plunger12 in a rest position. The spring 14 holds the end surface 13 of theplunger 12 in engagement with the inner side of a central portion 15 ofthe diaphragm 8 having one or more perforations 11 defined therein. Thearrows in FIG. 2 indicate how the fluid is prevented from entering intothe space between the plunger 12 and the diaphragm 8 and from leakingout therefrom. In this position, the plunger 12 can be regarded as beinglike a valve body that engages a valve seat.

FIGS. 3 and 4 illustrate how the diaphragm 8 is made to vibrate oroscillate by means of the driving member 9 and the diaphragm 8 may flexin one or the other direction. FIG. 3 illustrates how the diaphragm 8has flexed outwardly so that its central portion 15 is moved away fromthe end surface 13 of the plunger 12 and how the spring 14 is unable tomove the plunger 12 quickly enough so that its end surface 13 is kept incontinual engagement with the inside surface of the diaphragm. Thisinability is due to the inertia of the plunger and the spring. As aresult, a gap or space 16 is defined between the diaphragm 8 and the endsurface 13 of the plunger 12. The fluid may enter into this space 16, asindicated by the arrows in FIG. 3. When the driving member 9 is urgingthe diaphragm 8 in the opposite direction, the fluid may enter the space16 between the surface 13 and the central portion 15. The diaphragm 8that is approaching the end surface 13 will cause the fluid to leave thespace 16 through the hole or the holes 11 disposed at the centralportion of the diaphragm. A certain amount of the fluid disposed in thespace 16 may be pressed out radially along the inside of the diaphragmarea and remain inside the casing 1.

The enlarged cut out portion of FIG. 4 shows a space 17 defined betweenthe diaphragm 8 and the plunger 12. This space 17 appears when thediaphragm 8 flexes inwardly and meets the plunger 12. The figure alsoshows how the fluid adjacent the end surface 13 of the plunger 12 issucked inwardly towards the holes 11 and ejected therefrom by thecurrent or suction forces at the holes 11.

The figure only shows an embodiment of the present invention when boththe diaphragm 8 and the end surface 13 of the plunger 12 are flat. Theplunger 12 that engages the diaphragm portion is also flat.

It should be understood that the diaphragm 8 may be shaped differently.Accordingly, the membrane or a portion of the membrane that is oppositethe plunger 12 or the body 12 when the plunger is in its rest positionmay be convex or concave shaped in order to provide a sufficient sealwhen the plunger is in its rest position, as shown by membranes 15' and15" in FIGS. 5 and 6, respectively. Complimentary concave and convexshaped plungers 12' and 12" are also shown in FIGS. 5 and 6,respectively.

It is also possible to use a more or less conically shaped diaphragm15'" and a conically shaped end surface of a plunger 12'" that isadapted to sealingly engage the conically shaped diaphragm 15'", asshown in FIG. 7.

In the embodiments shown, the plunger only moves at a right angletowards the diaphragm but it should be understood that essentially thesame effect may be achieved if the plunger moves along a path that isoblique relative the diaphragm.

The invention is not to be regarded as limited to the embodimentsdescribed herein and shown in the figures but can be modified in severalways within the scope of the appended claims.

I claim:
 1. A diaphragm pump comprising:a housing having an openingdefined at one end; a diaphragm attached to the housing to extend overthe opening; an inlet defined in the housing for receiving a fluid; adriving element attached to the housing, the driving element being indriving engagement with the diaphragm to vibrate the diaphragm; anorifice defined in the diaphragm, the orifice being adapted to permit adischarge of the fluid therethrough; a plunger disposed within thehousing, the plunger being movable within the housing; and a springdisposed within the housing for biasing the plunger towards thediaphragm so that the plunger sealingly engages the diaphragm.
 2. Adiaphragm pump according to claim 1, wherein the plunger is asubstantially cylindrical body having two opposite end surfaces, one ofthe end surfaces facing the diaphragm and the opposite end surfacefacing the spring.
 3. A diaphragm pump according to claim 1 wherein thehousing has a protrusion having a bottom, the protrusion defining arecess adapted for receiving the plunger and the spring, the springbeing disposed between the plunger and the bottom.
 4. A diaphragm pumpaccording to claim 1 wherein the diaphragm has a periphery and thedriving element is annular and disposed at the periphery of thediaphragm.
 5. A diaphragm pump according to claim 1 wherein thediaphragm is movable between a most inward position and a most outwardposition relative to the housing, the spring providing a biasing forceagainst the plunger to bias the plunger to touch the diaphragm when thediaphragm is in its most inward position.
 6. A diaphragm pump accordingto claim 1 wherein the spring provides a biasing force that is adaptedto bias the plunger against the diaphragm so that the plunger sealinglyengages the diaphragm and covers the orifice.
 7. A diaphragm pumpaccording to claim 1 wherein at least a portion of the diaphragm is flatand one end of the plunger is flat.
 8. A diaphragm pump according toclaim 1 wherein at least a portion of the diaphragm is convex shapedwhen the diaphragm is in a rest portion and one end of the plunger iscurved and adapted to fit into the convex shaped diaphragm.
 9. Adiaphragm pump according to claim 1 wherein at least a portion of thediaphragm is conical shaped when the diaphragm is in a rest position andone end of the plunger is conical shaped and adapted to fit into theconical shaped diaphragm.
 10. A diaphragm pump according to claim 1wherein the driving element is a piezoelectric device.
 11. A diaphragmpump according to claim 1 wherein the driving element is anelectromagnetic device.
 12. A diaphragm pump according to claim 1wherein the diaphragm is adapted to oscillate relative to the housing.13. A diaphragm pump according to claim 1 wherein at least a portion ofthe diaphragm is concave shaped when the diaphragm is in a rest portionand one end of the plunger is curved and adapted to fit into the concaveshaped diaphragm.